手机自动化测试：Appium源码分析之跟踪代码分析九
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// set up distributed logging before everything else
var npmlog = global._global_npmlog = require('npmlog');
// npmlog is used only for emitting, we use winston for output
//不利用npmlog输出信息,而是利用winston来输出，所以将npmlog的等级设置为silent
npmlog.level = "silent";
//日志管理系统
var winston = require('winston')
//文件操作模块
, fs = require('fs')
//获取系统信息的模块
, os = require('os')
//处理和转换文件路径
, path = require('path')
//工具模块
, util = require('util');
//日期处理模块
require('date-utils');
//log等级定义
var levels = {
debug: 1
, info: 2
, warn: 3
, error: 4
};
//各等级对应的字体颜色
var colors = {
info: 'cyan'
, debug: 'grey'
, warn: 'yellow'
, error: 'red'
};
//定义log等级对应关系的字典
var npmToWinstonLevels = {
silly: 'debug'
, verbose: 'debug'
, info: 'info'
, http: 'info'
, warn: 'warn'
, error: 'error'
};
var logger = null;
//时区
var timeZone = null;
//堆栈
var stackTrace = null;
// capture any logs emitted by other packages using our global distributed
// logger and pass them through winston
npmlog.on('log', function (logObj) {
//根据传入的参数，得到对应的log等级，如果参数未被定义过，也就是说在字典中未找到，那么就设置为info
var winstonLevel = npmToWinstonLevels[logObj.level] || 'info';
//获得消息体
var msg = logObj.message && logObj.prefix ?
(logObj.prefix + ": " + logObj.message) :
(logObj.prefix || logObj.message);
logger[winstonLevel](msg);
console.log("==========npmlog.on=================");
});
//将当前日期转化为YYYY-MM-DD HH24:MI:SS:LL形式
var timestamp = function () {
var date = new Date();
if (!timeZone) {
//date.getTimezoneOffset()时差，精确到分钟，乘以60000，精确到毫秒数
date = new Date(date.valueOf() + date.getTimezoneOffset() * 60000);
}
return date.toFormat("YYYY-MM-DD HH24:MI:SS:LL");
};
// Strip the color marking within messages.
// We need to patch the transports, because the stripColor functionality in
// Winston is wrongly implemented at the logger level, and we want to avoid
// having to create 2 loggers.
//解决winston在日志实现上bug，有时候会产生2个logger器
function applyStripColorPatch(transport) {
var _log = transport.log.bind(transport);
transport.log = function (level, msg, meta, callback) {
var code = /u001b[(d+(;d+)*)?m/g;
msg = ('' + msg).replace(code, '');
_log(level, msg, meta, callback);
};
}
//将log信息传输到控制台上
var _createConsoleTransport = function (args, logLvl) {
var transport = new (winston.transports.Console)({
name: "console"
, timestamp: args.logTimestamp ? timestamp : undefined
, colorize: !args.logNoColors
, handleExceptions: true
, exitOnError: false
, json: false
, level: logLvl
});
if (args.logNoColors) applyStripColorPatch(transport);
return transport;
};
//将log信息传输到文件中
var _createFileTransport = function (args, logLvl) {
var transport = new (winston.transports.File)({
name: "file"
, timestamp: timestamp
, filename: args.log
, maxFiles: 1
, handleExceptions: true
, exitOnError: false
, json: false
, level: logLvl
}
);
applyStripColorPatch(transport);
return transport;
};
//将log信息传输到webhook中,webhook就是将log信息传输到某一个指定url上，将log信息传输到web服务器上
var _createWebhookTransport = function (args, logLvl) {
var host = null,
port = null;
if (args.webhook.match(':')) {
var hostAndPort = args.webhook.split(':');
host = hostAndPort[0];
port = parseInt(hostAndPort[1], 10);
}
var transport = new (winston.transports.Webhook)({
name: "webhook"
, host: host || '127.0.0.1'
, port: port || 9003
, path: '/'
, handleExceptions: true
, exitOnError: false
, json: false
, level: logLvl
});
applyStripColorPatch(transport);
return transport;
};
//管理分配上面三种log表现形式：控制台，文件，web。其中控制台是必须的，文件和web是根据配置来产生的
var _createTransports = function (args) {
var transports = [];
var consoleLogLevel = null,
fileLogLevel = null;
if (args.loglevel && args.loglevel.match(":")) {
// --log-level arg can optionally provide diff logging levels for console and file separated by a colon
var lvlPair = args.loglevel.split(':');
consoleLogLevel = lvlPair[0] || consoleLogLevel;
fileLogLevel = lvlPair[1] || fileLogLevel;
} else {
consoleLogLevel = fileLogLevel = args.loglevel;
}
transports.push(_createConsoleTransport(args, consoleLogLevel));
if (args.log) {
try {
// if we don't delete the log file, winston will always append and it will grow infinitely large;
// winston allows for limiting log file size, but as of 9.2.14 there's a serious bug when using
// maxFiles and maxSize together. https://github.com/flatiron/winston/issues/397
if (fs.existsSync(args.log)) {
fs.unlinkSync(args.log);
}
transports.push(_createFileTransport(args, fileLogLevel));
} catch (e) {
console.log("Tried to attach logging to file " + args.log +
" but an error occurred: " + e.msg);
}
}
if (args.webhook) {
try {
transports.push(_createWebhookTransport(args, fileLogLevel));
} catch (e) {
console.log("Tried to attach logging to webhook at " + args.webhook +
" but an error occurred. " + e.msg);
}
}
return transports;
};
var _appDir = path.dirname(require.main.filename);
//将堆栈信息转化为字符串
var _stackToString = function (stack) {
var str = os.EOL + " [------TRACE------]" + os.EOL;
var len = stack.length < 15 ? stack.length : 15;
for (var i = 0; i < len; i++) {
var fileName = stack[i].getFileName();
// ignore calls from this file
if (fileName === __filename) continue;
var substr = " at ";
try {
var typeName = stack[i].getTypeName();
substr += util.format("%s.%s (%s:%d:%d)" + os.EOL, typeName, stack[i].getFunctionName(),
path.relative(_appDir, stack[i].getFileName()), stack[i].getLineNumber(),
stack[i].getColumnNumber());
str += substr;
} catch (e) { }
}
return str;
};
var _addStackTrace = function (fn, stackTrace) {
var _fn = fn;
return function (msg) {
//os.EOL为行结束符
_fn(msg + os.EOL + _stackToString(stackTrace.get()) + os.EOL);
console.log("==========_addStackTrace=================");
};
};
//log系统初始化
module.exports.init = function (args) {
// set de facto param passed to timestamp function
timeZone = args.localTimezone;
// by not adding colors here and not setting 'colorize' in transports
// when logNoColors === true, console output is fully stripped of color.
if (!args.logNoColors) {
winston.addColors(colors);
}
//初始化log器，准备控制台输出(文件和webhook都准备好)
logger = new (winston.Logger)({
transports: _createTransports(args)
});
//设置log等级
logger.setLevels(levels);
// 8/19/14 this is a hack to force Winston to print debug messages to stdout rather than stderr.
// TODO: remove this if winston provides an API for directing streams.
//将debug的信息转化为info等级的lgo
if (levels[logger.transports.console.level] === levels.debug) {
logger.debug = function (msg) { logger.info('[TesterHome] ' + msg); };
}
//如果允许同步堆栈信息，就要在相应的log输出信息中追加这些信息
if (args.asyncTrace) {
stackTrace = require('stack-trace');
//将堆栈信息追加到等级为info的log信息中，后面两个类似
logger.info = _addStackTrace(logger.info, stackTrace);
logger.warn = _addStackTrace(logger.warn, stackTrace);
logger.error = _addStackTrace(logger.error, stackTrace);
}
};
//以get函数对外提供
module.exports.get = function () {
if (logger === null) {
exports.init({});
}
return logger;
};